<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>标题标记</title>
</head>
<body>
    以下标题的样式：
        <h1>H1标题大小<h1>
        <h2>H2标题大小<h2>
        <h3>H3标题大小<h3>
        <h4>H4标题大小<h4>
        <h5>H5标题大小<h5>
        <h6>H6标题大小<h6>
         
</body>
</html>